Bennett Mechanical Test Bennett Mechanical Work and Energy Questions and Answers 2

Question 1

A 1000 W motor runs for 30 seconds. How much energy does it consume?

Accepted Answer

30,000 J

Answer

Energy = Power × time = 1000 × 30 = 30,000 J.

Question 2

Which form of energy is stored in a stretched rubber band?

Accepted Answer

Elastic potential energy

Answer

A stretched rubber band stores elastic potential energy due to its deformation.

Question 3

A 2 kg object moves at 4 m/s. What is its kinetic energy?

Accepted Answer

16 J

Answer

KE = ½mv² = ½ × 2 × 4² = 16 J.

Question 4

According to the law of conservation of energy, what happens to total energy in a closed system?

Accepted Answer

It remains constant

Answer

Energy cannot be created or destroyed; it only changes form, so total energy in a closed system is constant.

Question 5

A 60 W light bulb operates for 2 hours. How much energy does it consume?

Accepted Answer

432,000 J

Answer

Energy = 60 W × (2 × 3600 s) = 60 × 7200 = 432,000 J.

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